Cavity-backed slot antennas are well suited for applications on aerospace vehicles and other vehicles. Such antennas can be recessed in the vehicle structure and create virtually no drag or effect to air flow over the vehicles surface. However, the maximum power handling capability of any antenna, at a given density altitude is determined by the maximum electric field strength that exists within the antenna. The maximum electric field strength of a cavity backed slot antenna is determined by the dimensions of the feed network geometry. Existing cavity-backed antenna elements typically use an air strip line feed to excite the slot radiator. The strip line has a very non-uniform current over the cross-section of the center conductor and the electric field between the center conductor and the outer conductor peaks significantly at the edges of the strip line center conductor (the field strength at the edge of the center conductor is typically 2-3 times higher than the field strength at the center of the center conductor. The electric current that flows on the strip line center conductor is crowded to the edges of the center conductor and the result is significant ohmic loss and heating under high power conditions. The transition from the coaxial feed to the strip line also typically results in enhanced electric field strengths in the transition region owing to the geometrical limitations of using the strip line.